Re: [PATCH 2/5] iommu/dart: Skip reset for locked DARTs

Locked DARTs cannot be reconfigured, therefore the reset/restore
procedure can't work and should not be needed. Skip it, allowing locked
DARTs to probe.

Co-developed-by: Hector Martin <redacted>
Signed-off-by: Hector Martin <redacted>
Signed-off-by: Alyssa Rosenzweig <redacted>
---
  drivers/iommu/apple-dart.c | 24 ++++++++++++------------
  1 file changed, 12 insertions(+), 12 deletions(-)

diff --git a/drivers/iommu/apple-dart.c b/drivers/iommu/apple-dart.c
index 460cf96bc8001e051916f356d5d175b35e36c608..9c74a95eb7e819e94ab2fb47ed0d411a1eba8bf7 100644
--- a/drivers/iommu/apple-dart.c
+++ b/drivers/iommu/apple-dart.c

@@ -452,17 +452,9 @@ apple_dart_t8110_hw_invalidate_tlb(struct apple_dart_stream_map *stream_map)
  
  static int apple_dart_hw_reset(struct apple_dart *dart)
  {
-	u32 config;
  	struct apple_dart_stream_map stream_map;
  	int i;
  
-	config = readl(dart->regs + dart->hw->lock);
-	if (config & dart->hw->lock_bit) {
-		dev_err(dart->dev, "DART is locked down until reboot: %08x\n",
-			config);
-		return -EINVAL;
-	}
-
  	stream_map.dart = dart;
  	bitmap_zero(stream_map.sidmap, DART_MAX_STREAMS);
  	bitmap_set(stream_map.sidmap, 0, dart->num_streams);

@@ -1151,9 +1143,11 @@ static int apple_dart_probe(struct platform_device *pdev)
  	}
  
  	dart->locked = apple_dart_is_locked(dart);
-	ret = apple_dart_hw_reset(dart);
-	if (ret)
-		goto err_clk_disable;
+	if (!dart->locked) {
+		ret = apple_dart_hw_reset(dart);
+		if (ret)
+			goto err_clk_disable;
+	}
  
  	ret = request_irq(dart->irq, dart->hw->irq_handler, IRQF_SHARED,
  			  "apple-dart fault handler", dart);

@@ -1192,7 +1186,9 @@ static void apple_dart_remove(struct platform_device *pdev)
  {
  	struct apple_dart *dart = platform_get_drvdata(pdev);
  
-	apple_dart_hw_reset(dart);
+	if (!dart->locked)
+		apple_dart_hw_reset(dart);

+
  	free_irq(dart->irq, dart);
  
  	iommu_device_unregister(&dart->iommu);

@@ -1325,6 +1321,10 @@ static __maybe_unused int apple_dart_resume(struct device *dev)
  	unsigned int sid, idx;
  	int ret;
  
+	/* Locked DARTs can't be restored, and they should not need it */
+	if (dart->locked)
+		return 0;
+
  	ret = apple_dart_hw_reset(dart);
  	if (ret) {
  		dev_err(dev, "Failed to reset DART on resume\n");